Supply voltage (Vcc) scaling is the most effective technique for reducing energy consumption of digital integrated circuits. As Vcc reduces, the adverse impact of process parameter variations on silicon performance and reliable operation increases. In addition, today's silicon execute over a wide dynamic operational range (Vcc, Frequency, temperature, etc.). Device reliability, including logic data retention concerns are most pronounced in the lowest-power modes and at the minimum supply voltages (Vmin). Vmin is the minimum operating voltage below which circuits (e.g., sequential units) no longer operate correctly (e.g., the state held in the sequential unit flips).